This invention relates to gas turbine engines and particularly to a combustion chamber for gas turbine engines for use in a motor vehicle.
In an automotive gas turbine, it is relatively simple to design the combustion chamber so that emissions of carbon monoxide and hydrocarbons are minimized. Considerable difficulties are encountered in reducing nitrous oxide emissions because of the variation in fuel-air ratio of the combustion gases under various turbine load conditions. In particular, when the combustion gas is a homogeneous mixture of fuel and air, low nitrous oxide emissions are experienced for relatively lean fuel mixtures, but substantially higher nitrous oxide emissions occur for richer mixtures, which are required at higher engine load conditions.
Prior German Patent Application No. 2,460,709 discloses a combustion chamber for a gas turbine wherein the flame tube is connected to the outlet of a prechamber containing an air inlet and fuel injector at the end of the prechamber away from the flame tube. The prechamber is provided with peripheral air intake openings in the vicinity of the flame tube which are mechanically adjustable in order to change the fuel-air mixture under various engine operating conditions. Because of their location adjacent the prechamber and flame tube, the adjustable air intake openings are exposed to the high temperatures of the flame tube and consequently subject to a breakdown or malfunctioning.
It is therefore an object of the present invention to provide a new and improved combustion chamber for a gas turbine, having reduced emissions of nitrous oxides.
It is a further object to provide such a combustion chamber wherein the combustion process is varied without mechanical control to provide low emission combustion under a variety of operating conditions.